Process for the concentration of oxidized ores



I Patented Feb. 1d, 1926.

UNITED STATES.

STUART CROASDALE, OF DENVER, COLORADO.

No Drawing.

To all whom it may concern:

Be it known that I, STUART CRQASDALE, a citizen of the United States, residing at Denver, in the county of Denver and State 5 of Colorado, have invented certain new and useful Improvements in Processes for the Concentration of Oxidized Ores, or which the following is a specification.

My invention relates to a process of con- I centrating ores by flotation and its primary object resides in subjecting comminuted ores in the rocess of concentration commonly known in the art as a flotation process, to a novel treatment whereby those of their mineral particles which heretofore have not been amenable to concentration, are made subject to the aflinity and the buoyant influence of a flotation agent.

The present application is a continuation 0 in part of my ap lication for patent Serial No. 503,355, filed eptember 26,1921.

My invention is particularlyadapted for the treatment of oxidized ores, it being a well known metallurgical fact that minerals of oxidized character. do not adsorb the 'oelic or gaseous re -agents to an extent necessary for their flotation, and, therefore, cannot be concentrated-as readily by a-flotation process'as those consisting entirely or in part of 80 sulfides. Y

My rocess consists briefly in mixing the ore under treatment in a finely divided state, with a soluble sulfide re-agent, a frothing agent and an oil or other hydrocarbon compound containing a substantial percentage of'what are generally termed unsaturated hydrocarbons such as are contained in mineral oils, either in their natural condition or artificially obtained. Y

The unsaturated hydrocarbons suitable for use in the rocess are more particularly those which be ong to the olefine series.

The action of the sulfide re-agent upon the oxidized ore particles causes a physical change? in their surface character which renders them capable of ready flotation in the usual manner by oils or hydrocarbons of the kind hereinabove referred to, with the addition of a suitable frothing agent, as for example, pine oils or wood or coal tar creosotes an other products of their distillation.

It isdesired to clearlyindicate that in order to effect a successful flotation and re- PBOGESS FOR THE CONCENTRATION OF OXIDTZED OBES. v

Application filed January 8, 1923. Serial No. 811,473.

that a successful recovery of'the oxidized ore occurs.

Examples of the unsaturated hydrocarbons which I prefer to use are as follows: 1; A crude petroleum of parafiin or, asphaltic base but preferably the former, containing the highest obtainable ercentage of unsaturated hydrocarbons. grude pe- 90% unsaturated hydrocarbons.

2. Distillation fractions of crude etroleum having the approximate viscosity of the gas oil fraction and containing their relative percentages of unsaturated hydrocarbons. In statlng the approximate viscosity of the gas oil fractlon, I include with the gas oil fraction the kerosene fraction on one side and the light lubricating oil fraction on the other.

, 3. Products obtained from cracking petroleum under pressure, which have still higher percentages of unsaturated hydrocarbons than the original crude petroleum.

4. Unrefined products obtained from the distillation of oil shales, which contain from 30% to 80% of unsaturated hydrocarbons, according to the 'method of distillation. These oils contain a high percentage of unsaturated hydrocarbons due to the partial cracking of the oils during distillation.

The change produced 'on the surface of the mineral particles consists in their envelopment by a thin adsorbed coating or film of the sulfide re-agent roduced by the chemical. aiunity of the su de re-agent for the mineral without chemical re-action noticeable to the naked eye.

While there is a ossibility of a slight chemical reaction ta 'n place on the surface of the oxidized minerals in order to cause them to adsorb the films of the revtroleums contain, as a rule, from 15% to I 9 7.3% of le'adin, anoxidized' condition, were drocarbonaceous compound, the sulfide reagent and a frothing agent, in water to form a pulp of the consistency usually used in the flotation process.

In this connection, it will be understood I that the oil, the sulfide re-agent and the frothing agent may-be added while the material is being ground instead of afterward should this method of intermixing the ore and ingredients be found to be more convenient or eflicient in handling a particular grade or kind of crude material.

The ore pulp is fed into a tank of the kind usually employed in a flotation process and the hydrocarbon compound actingupon the [oxides coated by the sulfide re-agent, causes with the addition of a frothing agent, a concentration of these mineralsat the surface of the liqid mass from Where they are removed in an overflowing froth as usual.

The quantities in which the sulfide reagent, the hydrocarbon compound and the frothing agent are used must necessarily bev varied in accordance with the nature of the material under treatment, it being evident that by reason of the infinite variations in the composition of" ores, no definite proportions can be relied upon for. the successful application of the present process to different ores and under different conditions.

1 Asa'n example, in the treatment of a copper ore having a total copper content of 3.4% of which 1.7 8% was sulfides of copper and 1.62% oxidized copper, it; was found advantageous to use to each ton of the ma-' "teria'l20 pounds ofan approximately- 30% ery of the sulfides of copper had been madesolution, of calcium L poly-sulfide, 4 pounds of mineral oil (crude petroleum containing 68% of unsaturated hydrocarbons), and from 4 to, pound of afr'othing agent (hard wood creosote) In treating the mixture by the flotation. process, 85% of the oxidized cop er was concentrated at the surface of the liquid, after a commercial recovin the usual'm'annen' .y

:In a treatment of a lead silver ore con-' taininga 6.7 ounces' of silver per ton .and

approximately of unsaturated hydro-H carbons, and a frothingagent consisting of use in :my process of concentration are the poly-sulfides of the alkaline earth metals and more particularly the poly-sulfides of calcium. v By the use of these poly-sulfides, the efliciency of the process is not impaired by the introduction of soluble salts since only salts of a very low degree of solubility are entered into the material.

, The use of oly-sulfides of the alkaline earth metals urthermore is advantageous in that they insure the presence of a higher percentage of active'sulfur in combination with the alkaline earth metal than is obtainable in the use of the-normal monosulfides or di-sulfides of the same metals, it being observed that the highest filming actions 'are obtained with a minimum alkalinity of the ore pulp. a

Still another advantage of the use of poly-sulfides of the alkaline earth metals and more particularly the poly-sulfides of calcium, resides in the simple manner in which this compound may. be prepared and the low-cost at which it can be produced.

Among the various poly-sulfides of the alkaline earth metals, penta-sulfide of calcium has been found to be particularly suitable as a re-agent in my improved flotation process. I 7

Under certain conditions, the sulfides of the alkaline metals or 'hydrogen sulfides 7 may be found to give satisfactory results al- \though the poly-sulfides of the alkaline earth metals are more desirable since alkaline metal sulfides have a strong sulfidizing ac tion which is undesirable in the present duce an excess'of alkalinity in the ore pulp and .thereby prevent efficient commercial recovery of the values.

I am aware" that the use of sulfide reagents in a flotation process has been heretofore attempted and I desire it understood that my invention resides not in the-use of a sulfide re-agent as a means for sulfidization, but in its use for the production of an adsorbed coating of the sulfide re-agent upon the oxidized mineral particles by which the commercial recovery-of said articles in their natural state by use 0 an oil' or other hydrocarbon containing unsaturated h drocarbons, in conjunction with a suitable fi'othing -agent,-is made possible.

It should be understood that -my im'-' proved process resides particularly in the production of an adsorbed film on the sur face of the oxidized mineral particles and that no change takes place in the orepulp mixture as in other processes heretofore used'for the same purpose, and it should also be noted that in my process there is no visible chemical re-action between the sulfide re-agent andthe oxidized mineral particles.

It will furthermore be evident that the process is also beneficial in the treatment of substantial partially oxidized ores where the residual sulfide particles of mineral may be coated with an oxidized surface.

The terms hydrocarbons containing a ercentage of unsaturated hy- 1 drocarbons" and hydrocarbons containing a substantial percents. e ofunsaturated h drocarbons of the ole 6 series as used in the claims is to be interpreted to mean those compounds which outside of minor impurities are substantially composed of hydrogen and carbon. 'It specifically excludes the hydrocarbon derivatives such as the oxygen compounds known under the name of alco- -hols or sulphonated hydrocarbon comsaturated hydrocarbons of the ole pounds.

Having thus described my invention, what I claim and desire tosecure by Letters Patent is:

1. The process of concentrating by flotation' ores containing oxidized minerals to more completely recover the same, the flotation being accomplished without forming any visible film of metallic sulfide on they surfaces of the mineral-particles, comprisin treating the ore-pulp in the presence of ca cium pentasulfide', a frothing agent, a relatively large amount of a hydrocarbon containing a substantial percenta e of e series and, recovering the concentrates.

2. The process of concentrating by flotation ores containing oxid minerals to more completely recover the same, the flotationbeing accomplished without forming any visible film of metallic sulfide on the surface of the mineral particles, comprising treating the ore-' ul in the presence of calcium polysulfidg, zffrothing agent and a relatively large amount of a hydrocarbon containing more than 50% of unsaturated hydrocarbons of the olefine series and recovering the concentrates.

3. The process of concentrating by flotation ores, containing oxidized minerals to more completely recover the same, the flotation being accomplished without forming any visible film of metallic sulfide on the relatively large amount of a hydrocarbon containing a substantialpercentage of unsaturated hydrocarbons and recovering the concentrates.

. 5. The process of concentrating by flotation ores containing oxidized minerals to more completely recover the same, the flotation being accomplished without forming any visible film of metallic sulfide on the surfaces of the mineral particles, comprising treating the ore-pulp in the presence of a polysulfide, a frothing agent, a relatively largeainount of a hydrocarbon containing a substantial percentage of unsaturated hydrocarbons and recovering the concentrates.

In testimony whereof'I have afiixed my signature.

STUART CROASDALE. 

